This invention relates generally to a food steamer and the associated method for steaming food and, more particularly, to a novel convection food steaming apparatus and the method which is particularly suitable for commercial, restaurant and institutional use.
The preparation and processing of foods, including frozen foods, in large quantities for schools, restaurants, hospitals and other institutions presents very distinct problems. With respect to frozen foods, a large component of the preparation time is waiting for the frozen foods to defrost and then subsequently cook. This time and labor can be minimized if the frozen food, along with other food items to be cooked, can go directly from the freezer to the cooker without an intermediate defrosting step. Food preparation of this type would eliminate the need for determining in advance the quantity of food required while still being ably to readily and promptly prepare and serve the food.
Several possibilities for cooking and/or defrosting food are available, including conventional ovens. However, conventional ovens have a low rate of heat transfer and, thus, are too slow for many applications, particularly the preparation of frozen food in very large quantities. Furthermore, conventional ovens often extract moisture and flavor from the food being prepared. Microwave ovens are an alternative to conventional ovens but offer limited capacity, often do not uniformly heat or defrost the food and do not significantly enhance or retain the flavor of the food being prepared.
Another alternative in the art of cooking is a steam oven to heat food items placed within a cooking chamber or compartment of the steamer. The art of steam cooking was developed as an alternative to cooking food in a free or forced convection hot air environment. Surface heat transfer coefficients associated with condensing saturated steam are typically greater than those of circulating hot air. As a result, foods cooked in a steam environment cook more quickly, retain more moisture, maintain nutritional values and are generally more pleasing in appearance and taste than food cooked in other environments.
However, known steam cooking devices and methods are not without problems. For example, the thermal efficiency of conventional steam cookers is relatively low, the flow of steam into the oven is often continuous so regardless of the quantity of food being steamed in the steamer or the various steaming requirements for the food, whether frozen or not, thermal energy of the steam is wasted. Known steam cookers do not take into account the varying demand for steam cooking times and environments for various food products. Kitchens, restaurants and other institutions often have varying demands for the types of food being steamed, but only have a single or limited number of steamers for preparing the food. As such, the food must be continually monitored or transferred into and out of the steamer thereby requiring a significant amount of attention, labor and time by the kitchen personnel for steaming a variety of different foods. Moreover, the steaming is inefficient because each time the steamer is opened the steam environment must be re-generated.
Another problem associated with known food steamers is the localized nature of the steam. Typically, the steam is released into the cooking chamber and, particularly in the case of large steaming chambers, becomes localized or focused in certain areas of the steamer. As a result, certain portions or items of foods in one location in the steamer become overcooked or excessively heated whereas other items require additional time because of the localized absence of cooking steam in that area of the steamer.
Another significant drawback with known food steamers, particularly pressure steamers is the potential injury to kitchen workers during operation of the steamer. In a conventional steamer in which steam is supplied to the oven by a boiler or the like. The oven has an access door which is typically manually sealed and must be manually opened. Prior to removing the steamed food, the pressurized steam must be released thereby adding another step to the cooking process. This rush of steam upon opening the door may cause severe burns particularly on the hands and face of the operator unless extreme care and caution is exercised when opening the food steamer door. High pressure devices are always a danger, particularly with the use of steam. Inattention to precautionary measures, which is particularly likely during extremely busy times, can cause severe injury. Moreover, pressure steamers cannot typically be opened quickly to add food as required and the cooking space of such pressure steamers is typically limited.
Furthermore, food steamers adequately sized for large institutions, restaurants, hospitals, schools or the like require a significant amount of floor space in the kitchen for the food steamer itself, steam boiler and other associated components. In many instances, floor space in food preparation areas, such as kitchens or the like, is at a premium and is often difficult to safely and conveniently accommodate the required components for an adequately sized food steaming system.